1. Field of the Invention:
This invention relates generally to refrigerating systems or chilling systems and more particularly, it relates to a control system for a hot gas bypass valve for centrifugal liquid chilling systems.
2. Description of the Prior Art:
In U.S. Pat. No. 3,174,298 issued to L. D. Kleiss on Mar. 23, 1965, there is described a control system for a water heating process wherein a first temperature transducer is connected to an outlet to provide a signal representative of the water temperature. This signal is compared with a set point which represents the desired water temperature at the outlet. A second temperature transducer is disposed in the inlet to provide a measurement of the water temperature at the inlet.
In U.S. Pat. No. 3,780,532 issued to D. K. Norbeck et al on Dec. 25, 1973 and assigned to the same assignee, there is described a control system for centrifugal compressors wherein the operation of pre-rotational vanes at the inlet to the compressor is controlled by measuring the temperature of the leaving chilled water.
In U.S. Pat. No. 3,522,711 issued to W. J. Shaughnessy on Aug. 4, 1970, there is disclosed a means for controlling a hot gas bypass valve of the solenoid type in a centrifugal chiller system by utilizing a signal representative of the position of the pre-rotation vanes to detect to a low-load condition and thus automatically opening the valve.